<template>
  <el-color-picker
    v-model="theme"
    :predefine="[
      '#409EFF',
      '#1890ff',
      '#304156',
      '#212121',
      '#11a983',
      '#13c2c2',
      '#6959CD',
      '#f5222d'
    ]"
    class="theme-picker"
    popper-class="theme-picker-dropdown"
  />
</template>

<script lang="ts">
import { useStore } from "@/store"
import {
  computed,
  defineComponent,
  getCurrentInstance,
  reactive,
  toRefs,
  watch
} from "vue"
import Loading from "@/utils/loading"
import { useI18n } from "vue-i18n"
const version = require("element-plus/package.json").version // element-ui version from node_modules
const ORIGINAL_THEME = "#409EFF" // default color

export default defineComponent({
  emits: ["change"],
  setup(_, context) {
    const { loading } = Loading()
    const store = useStore()
    const { t } = useI18n()
    const ctx = getCurrentInstance() as any
    const state = reactive({
      chalk: "",
      theme: store.state.settings.theme
    })

    const defaultTheme = computed(() => {
      return store.state.settings.theme
    })

    watch(defaultTheme, (value: string) => {
      state.theme = value
    })

    const getThemeCluster = (theme: string) => {
      const tintColor = (color: string, tint: number) => {
        let red = parseInt(color.slice(0, 2), 16)
        let green = parseInt(color.slice(2, 4), 16)
        let blue = parseInt(color.slice(4, 6), 16)
        if (tint === 0) {
          // when primary color is in its rgb space
          return [red, green, blue].join(",")
        } else {
          red += Math.round(tint * (255 - red))
          green += Math.round(tint * (255 - green))
          blue += Math.round(tint * (255 - blue))
          return `#${red.toString(16)}${green.toString(16)}${blue.toString(16)}`
        }
      }

      const shadeColor = (color: string, shade: number) => {
        let red = parseInt(color.slice(0, 2), 16)
        let green = parseInt(color.slice(2, 4), 16)
        let blue = parseInt(color.slice(4, 6), 16)
        red = Math.round((1 - shade) * red)
        green = Math.round((1 - shade) * green)
        blue = Math.round((1 - shade) * blue)
        return `#${red.toString(16)}${green.toString(16)}${blue.toString(16)}`
      }

      const clusters = [theme]
      for (let i = 0; i <= 9; i++) {
        clusters.push(tintColor(theme, Number((i / 10).toFixed(2))))
      }
      clusters.push(shadeColor(theme, 0.1))
      return clusters
    }

    const getCSSString = (url: string, variable: string) => {
      return new Promise((resolve) => {
        const xhr = new XMLHttpRequest()
        xhr.onreadystatechange = () => {
          if (xhr.readyState === 4 && xhr.status === 200) {
            ;(ctx as any)[variable] = xhr.responseText.replace(
              /@font-face{[^}]+}/,
              ""
            )
            resolve("成功")
          }
        }
        xhr.open("GET", url)
        xhr.send()
      })
    }

    const updateStyle = (
      style: string,
      oldCluster: string[],
      newCluster: string[]
    ) => {
      let newStyle = style
      oldCluster.forEach((color, index) => {
        newStyle = newStyle.replace(new RegExp(color, "ig"), newCluster[index])
      })
      return newStyle
    }

    watch(
      () => state.theme,
      async (value: string) => {
        if (value) {
          const oldValue = state.chalk ? state.theme : ORIGINAL_THEME
          const themeCluster = getThemeCluster(value.replace("#", ""))
          const originalCluster = getThemeCluster(oldValue.replace("#", ""))
          const loadingInstance = loading(t("theme.loading"))
          if (!state.chalk) {
            const url = `https://unpkg.com/element-plus@${version}/lib/theme-chalk/index.css`
            await getCSSString(url, "chalk")
          }
          const getHandler = (variable: string, id: string) => {
            return () => {
              const originalCluster = getThemeCluster(
                ORIGINAL_THEME.replace("#", "")
              )
              const newStyle = updateStyle(
                (ctx as any)[variable],
                originalCluster,
                themeCluster
              )
              let styleTag = document.getElementById(id)
              if (!styleTag) {
                styleTag = document.createElement("style")
                styleTag.setAttribute("id", id)
                document.head.appendChild(styleTag)
              }
              styleTag.innerText = newStyle
            }
          }

          const chalkHandler = getHandler("chalk", "chalk-style")
          chalkHandler()

          let styles: HTMLElement[] = [].slice.call(
            document.querySelectorAll("style")
          )
          styles = styles.filter((style) => {
            const text = style.innerText
            return (
              new RegExp(oldValue, "i").test(text) &&
              !/Chalk Variables/.test(text)
            )
          })
          styles.forEach((style) => {
            const { innerText } = style

            style.innerText = updateStyle(
              innerText,
              originalCluster,
              themeCluster
            )
          })

          context.emit("change", value)
          loadingInstance.close()
        }
      }
    )

    return {
      defaultTheme,
      ...toRefs(state)
    }
  }
})
</script>

<style lang="scss">
.theme-message,
.theme-picker-dropdown {
  z-index: 99999 !important;
}

.theme-picker .el-color-picker__trigger {
  height: 26px !important;
  width: 26px !important;
  padding: 2px;
}

.theme-picker-dropdown .el-color-dropdown__link-btn {
  display: none;
}
</style>
